Method of treating oil and gas wells

ABSTRACT

A two step process for treating an oil or gas well. The first step uses a cross linking agent, such as borax, as a preliminary wash for the well following drilling. The cross linking agent cleans the well of excess mud and pre-coats the tubing and the formation surfaces with the cross linking agent. The second step introduces a cement-polymer mixture into the well. A polymer, such as for example polyvinyl alcohol, that undergoes cross linking when exposed to the cross linking agent is employed. When the polymer comes into contact with the cross linking agent in the well, cross linking of the polymer occurs. This cross linking helps to prevent fluid loss into the formation. Also, because the cross linking agent wash previously cleaned the surfaces of the tubing and the formation, better bonding between the cement and the surfaces of the tubing and the formation occurs.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority as a continuation in part toU.S. Non-provisional patent application Ser. No. 12/019,933, filed onJan. 25, 2008, now U.S. Pat. No. 7,670,994, issued Mar. 2, 2010 andInternational Application No. PCT/US08/80838, filed Oct. 22, 2008 whichfurther claims priority to U.S. Non-provisional patent application Ser.No. 12/019,933, filed on Jan. 25, 2008, now U.S. Pat. No. 7,670,994,issued Mar. 2, 2010.

FIELD OF THE INVENTION

The present invention relates to a method for treating oil and gaswells. Various further embodiments relate to enhanced methods fortreating oil and gas wells.

DESCRIPTION OF THE RELATED ART

Previous methods of fluid loss control have been attempted by a one stepaddition of fluid loss control additive to the cement, which hopefullyreduces the ability of the liquid portion of the slurry from rapidlypenetrating a permeable zone at the formation face. This creates acritical dependence of the fluid control on the use of a fluid losscontrol additive that functions at the temperature of the permeablezone. Also, the cement slurry must be designed to complement therequirements of the fluid loss additive for rheology of the fluidportion of the cement slurry. Most fluid loss control additives thickenthe cement slurry into which they are mixed. Also, they may retard thehardening of the cement when it reaches its required destination. Todeal with such properties, it is common for service companies to havemany different fluid loss control additives and to select the “best fit”for the well conditions that are to be encountered.

SUMMARY OF THE INVENTION

Various embodiments of the present invention generally relate to methodsfor treating an oil and/or gas well. In an embodiment of a method of thepresent invention generally comprises washing a well borehole with awash composition comprising a cross linking agent, such as, for example,borax, and pumping a cement mixture into the borehole, to cement atleast a portion of the borehole, the cement mixture comprising a polymercomposition, such as, for example, a polyvinyl alcohol. In variousembodiments, the washing step at least partially cleans the well ofexcess mud and at least partially pre-coats the tubing and at leastpartially pre-coats the formation face with the cross linking agent.

The cement polymer mixture undergoes cross linking when exposed to thecross linking agent. In various embodiments, when the polymer in thecement mixture comes into contact with the wash composition's crosslinking agent, the polymer undergoes polymerization or cross linking.This cross linking helps to prevent fluid loss into the formation. Invarious embodiments, increased bonding between the cement mixture andthe surfaces of the tubing and the formation face is exhibited withcompositions and/or methods of the present invention.

Examples of components useful in the present invention can be found inU.S. Pat. Nos. 5,009,269; 5,850,880; 5,728,210, the contents of whichare hereby incorporated by reference as if they were reproduced hereinin their entirety.

As such, in various embodiments, compositions and methods are disclosedthat use a two stage process that allows washing, with a washcomposition, of the permeable zone of the well borehole's formation faceand cementing the well borehole with a cement mixture comprising apolymer composition.

This method is not as temperature dependant in down hole boreholeoperations, as with the fluid loss additives disclosed in U.S. Pat. Nos.5,009,269; 5,850,880; 5,728,210. In traditional processes using a washcomposition comprising a cross-linking agent and a cement mixturecomprising a polymer, operating conditions above about 200 degrees F.(93.3 degrees C.) results in partial degradation of the components ofthe wash composition and/or the cement mixture. However, surprisingly,embodiments of the present invention are capable of functioning fromnear freezing, i.e. about 32 degrees F. (0.0 degrees C.), to above 400degrees F. (204.4 degrees C.), or the degradation temperature of thepolymer.

In various embodiments, operating temperatures in excess of 400 degreesF. (204.4 degrees C.) are possible. Generally, an upper temperaturelimit is at or about the temperature where the components of the washcomposition and/or cement mixture degrade. In an embodiment, the washcomposition's components degrade at above 400 degrees F. (204.4 degreesC.). In an alternate embodiment, the wash composition's componentsdegrade at about 250 degrees F. (121.1 degrees C.). In an alternateembodiment, the wash composition's components degrade above 400 degreesF. (204.4 degrees C.).

In various embodiments, temperatures below zero degrees Celsius aredifficult to operate in because the components of the drilling mud beginto change phase or freeze. Typically, such environments are found inareas with permafrost. Additives can be included in the drilling mud tolower the freezing point but attention should be had to interferencebetween the additives and the various components of the wash compositionand/or the cement mixture, as such, operating conditions below zero arepossible with various embodiments of the present invention.

In various embodiments, the cross linking agent to be used for washing,or as a “spacer” additive or drilling mud additive, is non toxic andenvironmentally clean. In an embodiment, the cost of this “spacer”additive for the wash is lower than a traditional complex chemical wash,as used in contemporary drilling operations. In various furtherembodiments, the cross linking agent is capable of being formulated as anon thickened water base fluid that will allow turbulent flow in theannulus at very low pump rates into the well borehole.

Turbulent flow is capable of producing a churning action within the wellborehole ahead of injected wash, as confirmed by laboratory studies.Additionally, the detergent action of the cross linking agent togetherwith the turbulent flow at least partially granulates excess mudadhering to the pipe and at least partially granulates the loose mud atthe formation face and carries the material out of the well.

In various embodiments, during this washing step using a cross linkingagent in the wash, a “seeding” will take place at the formation facewhich at least partially impregnates the mud cake with cross linkingagent. The concentration will vary depending on the permeability at theformation face. Typically, the concentration of the cross linking agentwill increase as the permeability of the formation face increases.

In various embodiments, a cross linking agent is capable being added todrilling mud, or “spacers”, to be available for polymerization with thepolymer. In such embodiments, fluid loss control is capable of beingobtained without a washing step, which step, in certain circumstances,might not be desired, such as when disposal of a wash composition is anissue. The drilling mud would impregnate the formation face with thecross linking agent and a subsequently pumped cement mixtures comprisinga polymer would cross link at or about the formation face.

In various embodiments, a polymer can be added to the cement mixtureeither as a dry component, a liquid component, or as a combination dryand liquid component. Typically, a polymer is comparatively low cost toconventional prior art complex fluid loss compositions. Further, withembodiments of the present invention, less material than conventionalfluid loss compositions is required. In one embodiment, less compositionis required because of the permeability block occurring at or about theformation-cement interface, where the reaction of the polymer and crosslinking agent takes place. Accordingly, the application of the crosslinking agent and the polymer is more targeted, producing less waste.

Otherwise, in various embodiments, if the reaction of the cross linkingagent and the polymer had taken place in the cement slurry prior toreaching the permeable formation face, such as when the cement slurry isinjected, the slurry would typically be much thicker because of thepolymerized polymer, thereby requiring more water to reduce theviscosity of the at least partially polymerized cement slurry.

Focusing the reaction at the pressure differential interface, orformation face, means that a cement mixture of an embodiment of thepresent invention requires less loading with viscosity lowering agentsand/or water/fluid.

In various embodiments, the cement mixtures are suitable forsubterranean applications such as well completion and remedialoperations. It is to be understood that “subterranean applications”encompass both areas below exposed earth and areas below earth coveredby water such as ocean or fresh water. In various embodiments, thecement mixtures include a sufficient amount of water to form a pumpableslurry.

The density of the cement mixtures may vary. In various embodiments, thecement mixtures may comprise a density of from about 4 lb/gallon toabout 23 lb/gallon. In alternative embodiments, the cement mixtures maycomprise a density of from about 12 lb/gallon to about 17 lb/gallon. Inother alternative embodiments, the cement mixtures may be low-densitycement mixtures with a density of from about 5 lb/gallon to about 12lb/gallon. In general, the density can be selected for the drillingoperation.

In various embodiments, the cement mixture comprises at least one cementsuch as hydraulic cement, which includes calcium, aluminum, silicon,oxygen, and/or sulfur and which sets and hardens by reaction with water.Examples of hydraulic cements include but are not limited to Portlandcements (e.g., classes A, C, G, and H Portland cements), pozzolanacements, gypsum cements, phosphate cements, high alumina contentcements, silica cements, high alkalinity cements, and combinationsthereof.

Type I Portland cement is known as common or general purpose cement. Itis commonly used for general construction especially when making precastand precast-prestressed concrete that is not to be in contact with soilsor ground water. The typical compound compositions of this type are 55%(C₃S), 19% (C₂S), 10% (C₃A), 7% (C₄AF), 2.8% MgO, 2.9% (SO₃), 1.0%Ignition loss, and 1.0% free CaO.

Type III has a relatively high early strength. Its typical compositionis 57% (C₃S), 19% (C²⁵), 10% (C₃A), 7% (C₄AF), 3.0% MgO, 3.1% (SO₃),0.9% Ignition loss, and 1.3% free CaO. The gypsum level may also beincreased a small amount. This gives the concrete using this type ofcement a three day compressive strength equal to the seven daycompressive strength of types I and II. Finally, other cement typesuseful in the cement blend of the present invention include (high-earlyset) HE and class C cements.

In various embodiments, a permeable, Micro-Cluster Silica Material maybe used in the cement mixtures. A Perlite-derived material capable ofuse in the present invention comprises microcellular fillers that areinert, inorganic, hollow glass particles with irregular sphericalgeometries. These particles are commercially available and sold underthe name Sil-cell® by Silbrico Corporation (Hodgkins, Ill.). Sil-cell®particles have a greater tensile strength than the usual sphericalbubbles. Sil-cell® has a low effective specific gravity (E.S.G.=0.18)and makes cost effective the manufacture of adhesives, auto body putty,cultured marble, coatings, wall patching compounds and stucco in whichSil-cell® is incorporated. The approximate composition of Sil-cell® is73% silicon dioxide, 17% aluminum oxide, 5% potassium oxide 3% sodiumoxide, 1% calcium oxide and trace elements.

The use of a low shear, folding type mixer is desirable to minimizeparticle breakage when using Sil-cell®. Thus, low shear testingprocedures were used to mix compositions with Sil-cell®. Tests wherehigh shear was used resulted in break-up of the structures and releaseof the entrapped gas. If the micro-clusters are completely broken-up,they no longer occupy the space in the liquid slurry needed toeventually intake the excess water used to initially mix and pump theslurry. The resulting slurry would be weakened when it hardens into setcement. Silbrico Corporation product Sil-43BC used in these preferredcomposition tests has an average particle size of about 35 microns witha range of 1 to 150 microns, and at least 95 percent less than 75microns. Generally, a grade of micro-cluster silica material has anaverage particle size ranging from about 30 to about 80 microns and arange of distribution from about 1 micron to about 200 microns. Moredesirably, the permeable, micro-cluster silica material has an averageparticle size ranging from about 30 to about 50 microns and a range ofdistribution from about 1 micron to about 200 microns and even better anaverage particle size ranging from about 30 to about 40 microns and arange of distribution from about 1 micron to about 150 microns.

The micro-clusters of glass bubbles in Sil-cell® have high permeability.The high permeability allows the micro-clusters to exchange void airspace (when hydraulic pressure is applied) with water from the cementmatrix that surrounds the micro-cluster. On the other hand, whenstructures that are not permeable (which is the case with micro-spheresand micro-beads), the micro-clusters would be subject to collapse underpressure. The use of crushable structures under high hydraulic pressureresults in dramatic rheology change when collapse takes place. This canrender such a slurry unpumpable or at a severe density change due to thecollapse of the air space.

The use of the permeable non-crushing, micro-clusters of glass bubblesavoids this possibility. The Ideal Gas Law can be used to calculate thedensity change with pressure. The increase in pressure is directlyrelated to the decrease in volume of gas. Also, simulated pressureconditions can be used in unique testing methods to predict the rheologyprofile and hydration characteristics of the cement mixture. Testing hasverified the integrity of the micro-clusters of glass bubbles afterwater has invaded the permeable structures under high hydraulicpressure. Thus, the micro-cluster retains its dimensions while fillingwith water from the surrounding fluid.

A sufficient amount of water is added to the cement mixture to make thecement mixture pumpable. The water may be fresh water or salt water,e.g., an unsaturated aqueous salt solution or a saturated aqueous saltsolution such as brine or seawater, or a non-aqueous fluid. The watermay be present in the amount of from about 16 to about 180 percent byweight of cement, alternatively from about 28 to about 60 percent byweight of cement. In general, any amount of water can be used as wouldbe understood by one of ordinary skill in the art.

In various embodiments an amount of cross linking agent is added toadequately cover the formation face. In an embodiment, the amount ofcross linking agent added is in excess of the amount of cross linkingagent needed to impregnate the formation face. In an alternateembodiment, the amount of cross linking agent added is 50% in excess ofthe amount of cross linking agent needed to impregnate the formationface. In an alternate embodiment, the amount of cross linking agentadded is 100% in excess of the amount of cross linking agent needed toimpregnate the formation face. In an alternate embodiment, the amount ofcross linking agent added is 200% in excess of the amount of crosslinking agent needed to impregnate the formation face. In an alternateembodiment, the amount of cross linking agent added is 500% in excess ofthe amount of cross linking agent needed to impregnate the formationface. In general, any amount of cross linking agent can be used and canbe governed by one of ordinary skill in the art based on coverage,results, cost, and/or the like.

In various embodiment an amount of polymer is added to is added toadequately cover the formation face and/or react with the cross linkingagent, thereby polymerizing. In an embodiment, the amount of polymeradded is in excess of the amount of polymer needed to polymerize on, in,or about the formation face. In an alternate embodiment, the amount ofpolymer added is 50% in excess of the amount of polymer needed topolymerize on, in, or about the formation face. In an alternateembodiment, the amount of polymer added is 100% in excess of the amountof polymer needed to polymerize on, in, or about the formation face. Inan alternate embodiment, the amount of polymer added is 200% in excessof the amount of polymer needed to polymerize on, in, or about theformation face. In an alternate embodiment, the amount of polymer addedis 500% in excess of the amount of polymer needed to polymerize on, in,or about the formation face. In general, any amount of polymer can beused and can be governed by one of ordinary skill in the art based oncoverage, results, cost, and/or the like.

In various embodiments of the present invention, the total amount byvolume of fluid loss additive need, wherein the fluid loss additivecomprises the polymer in the cement mixture and the cross linking agentin the wash composition (or drilling mud), is between about 1.0% and 90%of contemporary fluid loss additive. In an alternate embodiment, thetotal amount by volume of fluid loss additive needed is between about5.0% and 75% of contemporary fluid loss additive. In an alternateembodiment, the total amount by volume of fluid loss additive needed isbetween about 10% and 50% of contemporary fluid loss additive. In analternate embodiment, the total amount by volume of fluid loss additiveneeded is between about 15% and 25% of contemporary fluid loss additive.In an alternate embodiment, the total amount by volume of fluid lossadditive needed is 0% due to enhancements of various embodiments of thepresent invention.

In various embodiments of the present invention, the total amount byweight of fluid loss additive need, wherein the fluid loss additivecomprises the polymer in the cement mixture and the cross linking agentin the wash composition (or drilling mud), is between about 1.0% and 90%of contemporary fluid loss additive. In an alternate embodiment, thetotal amount by weight of fluid loss additive needed is between about5.0% and 75% of contemporary fluid loss additive. In an alternateembodiment, the total amount by weight of fluid loss additive needed isbetween about 10% and 50% of contemporary fluid loss additive. In analternate embodiment, the total amount by weight of fluid loss additiveneeded is between about 15% and 25% of contemporary fluid loss additive.In an alternate embodiment, the total amount by weight of fluid lossadditive needed is 0% due to enhancements of various embodiments of thepresent invention.

In various embodiments, a two stage method and also the type ofadditives used in the method should be a significant improvement forfluid loss prevention and permeable interface sealing. Such a techniqueor method could be utilized in any type of permeable situation tominimize leak off of fluid from a well bore, pond, lake, dam, etc.

The foregoing has outlined rather broadly the features of the presentdisclosure in order that the detailed description that follows may bebetter understood. Additional features and advantages of the disclosurewill be described hereinafter, which form the subject of the claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following description, certain details are set forth such asspecific quantities, sizes, etc. so as to provide a thoroughunderstanding of the present embodiments disclosed herein. However, itwill be obvious to those skilled in the art that the present disclosuremay be practiced without such specific details. In many cases, detailsconcerning such considerations and the like have been omitted inasmuchas such details are not necessary to obtain a complete understanding ofthe present disclosure and are within the skills of persons of ordinaryskill in the relevant art.

The following definitions and explanations are meant and intended to becontrolling in any future construction unless clearly and unambiguouslymodified in the following Description or when application of the meaningrenders any construction meaningless or essentially meaningless. Incases where the construction of the term would render it meaningless oressentially meaningless, the definition should be taken from Webster'sDictionary, 3rd Edition. Definitions and/or interpretations should notbe incorporated from other patent applications, patents, orpublications, related or not, unless specifically stated in thisspecification or if the incorporation is necessary for maintainingvalidity.

As used herein, the term “mud cake” means and refers to a caked layer ofclay adhering to the walls of a well or borehole, formed where the waterin the drilling mud filters into a porous formation during rotarydrilling.

As used herein, the term “lignosulfonate” means and refers tolignosulfonates, or sulfonated lignins, and are water-soluble anionicpolyelectrolyte polymers.

As used herein, the term “PVA” or “polyvinyl alcohol” means and refersto a partially hydrolyzed polyvinyl acetate polymer having at leastabout 80 percent of the acetate groups hydrolyzed. PVA has been adesired fluid loss control agent because of its low cost, its lack of aset retarding function, and the fact that it is not totally watersoluble, so that its effect on slurry viscosity is minimal. However, thePVA-based materials previously used have been less effective attemperatures above about 50 degrees C. because the PVA becomesessentially water-soluble. Also, PVA has not been particularly effectivein cement slurries formulated with fresh water.

As used herein, the terms “cross link” and “polymerize” are usedinterchangeably, unless such use would be irrational.

Various embodiments of the present invention can use any cross linkingagent. The cross-linking agent can comprise a borate releasing compoundor any of the well known transition metal ions which are capable ofcreating a cross-linked structure. Examples of cross-linking agentsinclude, but are not limited to, borate releasing compounds, a source oftitanium ions, a source of zirconium ions, a source of antimony ions anda source of aluminum ions. Generally any cross linking agent can beused.

A cross linking agent can come from any source, such as sodiumtetraborate, potassium tetraborate, boric acid, boron oxide, or calciumhexaboride, and the like. Titanate and zirconate cross-linking agentscan be used as full or partial substitutes for the water-solubleborates, but are not as preferred.

In general, any polymer can be used with various embodiments of thepresent invention, such as a polymerization product formed bypolymerizing a 2-acrylamido-2-methylpropane sulfonic acid,2-methacrylamido-2-methylpropane sulfonic acid, sulfonated styrene,vinyl sulfonic acid, allyl ether sulfonic acids such as propane sulfonicacid allyl ether, methallyl ether phenyl sulfonates, acrylic acid,methacrylic acid, maleic acid, itaconic acid,n-acrylamidopropyl-n,n-dimethyl amino acetic acid,n-methacrylamidopropyl-n,n-dimethyl amino acidic acid,n-acryloyloxyethyl-n,n-dimethyl amino acidic acid,n-methacryloyloxyethyl-n,n-dimethyl amino acidic acid,n-acryloyloxyethyl-n,n-dimethyl amino acidic acid,n-methacryloyloxyethyl-n,n-dimethyl amino acidic acid, crotonic acid,acrylamidoglycolic acid, methacrylamidoglycolic acid,2-acrylamido-2-methylbutanoic acid and 2-methacrylamido-2-methylbutanoicacid. Nonionic monomers which can be used in the formed (synthesized,intercalated) polymer include, but are not limited to, C₁-C₂₂ straightor branched chain alkyl or aryl acrylamide, C₁-C₂₂ straight or branchedchain n-alkyl or aryl methacrylamide, acrylamide, methacrylamide,n-vinylpyrrolidone, vinyl acetate, ethoxylated and propoxylatedacrylate, ethoxylated and propoxylated methacrylate, hydroxy functionalacrylates such as hydroxyethylacrylate and hydroxypropylacrylate,hydroxy functional methacrylates such as hydroxyethylmethacrylate andhydroxypropylmethacrylate, n,n-dimethylacrylamide,n,n-dimethylmethacrylamide, styrene, styrene derivatives and C₁-C₂₂straight or branched chain alkyl, aryl, allyl ethers, poly vinyl alcohol(PVA), and/or the like.

In embodiments utilizing PVA, at least in part, while not intending tobe bound, the mechanism by which PVA controls fluid loss is believed tobe different from that of other fluid loss materials. Most fluid lossadditives are high molecular weight polymers that are totallywater-soluble and form some type of a structure between the cementparticles, which reduces the permeability of the filter cake. PVA is nottotally water-soluble below about 50 degrees C., but is, instead,“water-swellable.” The individual PVA particles swell and soften to formsmall gel-balls in the slurry. These gel-balls deform by flattening, andbecome a part of the filter cake, greatly reducing the filter cakepermeability, thus giving extremely good fluid loss control. Because PVAis not totally water-soluble, it does not significantly increase theslurry viscosity. PVA does not retard the set of cement.

Variations in the degree of hydrolysis of the polyvinyl alcohol, themolecular weight of the polyvinyl alcohol, and the inclusion of up to 25percent by weight of substituents on the polyvinyl alcohol, such asmethacrylate, methmethacrylate and the like are within the scope of thepresent invention. In addition, the preferred embodiment can containcalcium sulfate in a form such as dihydrate or anhydrite, but present inan amount equivalent to from 0 to 60 percent by weight of calciumsulfate hemihydrate.

The surfactant can be any of a wide range of materials such asethoxylated alkyl phenols, ethoxylated primary or secondary alcohols,ethoxylated fatty alcohols, ethoxylated amines, ethoxylated amides,ethoxylated fatty acids, ethoxylated diamines, and ethoxylatedquaternary ammonium chlorides. Suitable surfactants are described indetail in U.S. Pat. No. 5,105,885, the contents of which are herebyincorporated by reference as if it was reproduced herein in itsentirety.

Antifoam materials useful in the present invention are usuallypolypropylene glycols but any suitable substitute can be utilized.

Cement retarding additives can also be added to the fluid lossadditives. At temperatures above 80 degrees F., cement sets in a shortperiod of time. Retarders, such as lignosulfonate materials, lengthenthe time the cement slurry will stay liquid, allowing the slurry to bepumped down the casing and back up the annulus before setting.

For embodiments comprising sulfonated polymer dispersing agents, suchmaterials are capable of being sulfonated polymelamine, sulfonatedpolystyrene or vinyl sulfonate polymers or mixtures of these. Othersulfonated polymer materials can be substituted provided that materialscan be prepared at low pH and neutralized to form salts of the polymers.The salts can be sodium, potassium, lithium, ammonium, calcium,magnesium, and the like. The sulfonated polymer is added in a quantityof 0.05 to 2.0 percent by weight of the cement. These sulfonatedpolymers are available in liquid or powdered form. The weight percentspecified is based on sulfonated polymer only and does not include theweight of any water that may be present in the liquid form.

In preparing the low viscosity dry mixed fluid loss control additive ofthe present invention, the components to the cement can be added as asingle blend, or as individual components, or in any combination ororder of addition.

The present invention is both compositions and methods for treating anoil or gas well and uses a cross linking agent, such as borax, as apreliminary wash for the well.

In various embodiments, a preliminary wash is capable of use to cleanthe well and pre-coat the tubing and the formation surfaces with thecross linking agent. In various embodiments, next, the cement mixturewith polymer is pumped into the well. When the polymer comes intocontact with the cross linking agent, the polymer undergoespolymerization or cross linking A cross linking agent helps to inhibitfluid loss into the formation. Also, because the cross linking agentwash cleaned the surfaces of the tubing and the formation, this resultsin better bonding between the cement and the surfaces of the tubing andthe formation.

In various embodiments, the interface of the cross-linker and polymerforms a wiper that at least partially cleans the wellbore and/or pipe ofexcess drilling mud during fluid circulation through an annulus. In anembodiment, a wiper of crosslinker and polymer is capable of use beforethe flow of cement into the annulus, thereby cleaning the annulus of atleast a portion of the excess mud. In an alternate embodiment, a wiperof crosslinker and polymer is capable of use immediately preceding theflow of cement into the annulus, thereby cleaning the annulus of atleast a portion of the excess mud. In various embodiments, the use of awiper of the present invention reduces drilling time because a separatecirculation cleaning step is not needed.

EXAMPLES

This invention has been proven using borax as a common cross linker forpolyvinyl alcohol (PVA) as the cross linking agent active ingredient byApplicants in the laboratory. These materials have been used before asfluid loss control agents, but only as a combined one step package. Whenused as a pre-blended or combined fluid loss control agent, the reactionof cross linking occurs in the cement slurry at the initial mixing timewhen water is added to the dry cement materials. As a result of thisreaction in the early slurry life, the cross linking reaction creates afragile structure that is temperature limited to about 200 degrees F.and requires a great excess of fluid loss material to control the fluidloss. Also the early reaction creates an increase in viscosity andpossible gelatin of the slurry. Such rheology problems increase thedemands on pumping equipment and change the desired state of turbulentflow to plug flow or laminar flow. Turbulent flow is an accepted methodto increase mud removal and subsequent bond improvement.

The addition of fine particulate material, such as for example calciumcarbonate, which has been ground or precipitated to less than 50 micronin average diameter, to the polyvinyl alcohol prior to mixing it withthe cement will be beneficial. These particles are carried by thepolyvinyl alcohol as it begins to soften in the aqueous slurry and cancontribute to the plugging action of the permeable formation. Theaddition of fine particulate material which is initially non-reactive inthe early reaction of cement hydration by has a surface binding to thepolyvinyl alcohol to carry by a gluing action the solid particles whichhelp to crate the “plug” for fluid loss prevention. The Portland cementparticles cannot usually function in this manner since upon hydration,the surface of the cement goes into solution in a “sloughing” action.Also, this is considerably more important if the particular cementslurry formulation has high gel strength properties. Such a gelledslurry will usually not allow the cement grains to move the desiredfluid loss plug area.

Applicants have documented using borax as a pre-wash and primer forcross linking a following polyvinyl alcohol in testing done inaccordance with American Petroleum Institute procedures as outlined inAPI RP 10 publication. Variation from the strict test procedures weredone in regard to simulation of a mud cake formation face as thepermeable interface for fluid loss tests. The standard filter medium was3.5 sq. in. in area. A 45 mm screen (No. 325) was supported by a 250 mmscreen (No. 60). In order to simulate a mud covered formation face, thetests were conducted by sandwiching a 1/16 smear of thick bentonite mudbetween Whatman No. 1 qualitative filter paper. The mud was soaked with2 ml of a solution containing 0.2 grams of borax. This “mud sandwich”was placed on the standard screen and fluid loss tests were conducted asoutline in the API procedures. To verify the improved control of theinvention, tests were run using the “mud sandwich” without borax andwithout the following polyvinyl alcohol.

Tests show that the polyvinyl alcohol, or other polymer, can be reducedto less than 0.1 percent by weight of dry cement and still maintainexcellent fluid loss control at the low temperatures. The conventionalpre-cross linked method uses as much as 10 times as much fluid lossadditive. Temperature limits easily were above the 200° F. (93.3° C.)limit of the conventional technique and were in fact found to extend tothe break down temperature of the polyvinyl alcohol which is above 300°F. (148.9° C.) for the particular polyvinyl alcohol tested. It isbelieved that the temperature could exceed this for a material withhigher temperature stability.

As such, various embodiments of the present invention comprise a methodfor inhibiting fluid loss from an oil and gas well, said methodcomprising the steps of, separately:

washing a well borehole with a wash composition, said wash compositioncomprising a cross linking agent, wherein said cross linking agent atleast partially impregnates a formation's face and

pumping a cement mixture into said well's borehole to cement at least aportion of a formation face, said cement mixture comprising a polymercomposition, wherein said polymer polymerizes in, on, or about saidformation's face upon exposure to said cross linking agent, therebyinhibiting fluid loss from said well's borehole to said formation. Invarious embodiments, the step of washing at least partially cleans thewell of excess mud. In various further embodiments, the step of washingat least partially impregnates at least one of said borehole's tubingand said borehole's formation face with said cross linking agent. Invarious embodiments, the cross linking agent is added to the well alongwith oil-based drilling mud or “spacer”. As such, in variousembodiments, the cross linking agent is at least one of borax, boricacid, water soluble borates, sodium borates, calcium borates, potassiumborates, titanates, zirconates, and mixtures thereof. In various furtherembodiments, a fine particulate material is added to the polymer priorto mixing it with the cement mixture, such as calcium carbonate. Invarious embodiments, the polymer is at least one of polyvinyl alcohol, alow viscosity partially hydrolyzed polyvinyl alcohol such as DuPontElvanol® 51-05S8.

Various further embodiments disclose a method for inhibiting fluid lossfrom an oil and gas well, the method comprising the steps of,separately:

washing a well with a reactant agent that creates a thickened reactionproduct when a secondary mixture is encountered, and

adding secondary mixture to the well's borehole which forms a thickenedreaction product upon exposure to the reactant, thereby inhibiting fluidloss from the well's borehole to the well borehole's formation.

In all embodiments, the step of washing is capable of being removed andthe cross linking agent is included with a drilling fluid circulated inthe well's borehole prior to adding the cement mixture.

Various further embodiments disclose a kit for inhibiting fluid lossfrom an oil and gas well comprising:

a wash composition, the wash composition comprising a cross linkingagent and

a polymer composition, wherein the polymer polymerizes in, on, or aboutthe formation's face upon exposure to the cross linking agent, therebyinhibiting fluid loss from the well's borehole to the formation.

Various further embodiments disclose a polymerized well borehole, thepolymerized well borehole formed by a method as herein disclosed.

A method for reducing an amount of fluid loss additive necessary toinhibit fluid loss from an oil and gas well, the method comprising thesteps of, separately:

washing a well borehole with a wash composition, the wash compositioncomprising a cross linking agent, wherein the cross linking agent atleast partially impregnates a formation's face and

pumping a cement mixture into the well's borehole to cement at least aportion of a formation face, the cement mixture comprising a polymercomposition, wherein the polymer polymerizes in, on, or about theformation's face upon exposure to the cross linking agent, therebyinhibiting fluid loss from the well's borehole to the formation, whereinbetween about 0.1% and about 90% by volume of a contemporary fluid lossadditive is used to inhibit fluid loss. In various embodiments, thefluid loss additive's components are the same as the components of thecontemporary fluid loss additive.

In all methods and kits herein disclosed, the cement mixture is capableof comprising a permeable, micro-cluster silica material present in anamount from about 10 percent to about 30 percent by weight of the cementmixture, wherein the permeable, micro-cluster silica material has anaverage particle size ranging from about 30 to about 80 microns and arange of distribution from about 1 micron to about 200 microns.

Further embodiments of the present invention comprise kits. Kits of thepresent invention are capable of containing different constituents orcomponents of the cement mixture. In an embodiment, a kit of the presentinvention comprises a polymer. In an alternate embodiment, a kit of thepresent invention comprises a polymer and a cross linking agent. Furtherkits may include, alternatively, retarders, defoamers, fluid lossadditives, glass beads, perlite and/or the like.

The invention may be embodied in other specific forms without departingfrom its spirit or essential characteristics. The described embodimentsare to be considered in all respects only as illustrative and notrestrictive. The scope of the invention is, therefore, indicated by theappended claims rather than by the foregoing description. All changes tothe claims that come within the meaning and range of equivalency of theclaims are to be embraced within their scope. Further, all publisheddocuments, patents, and applications mentioned herein are herebyincorporated by reference, as if presented in their entirety.

Additional Examples

Previous methods of fluid-loss control has been attempted by a one-stepaddition of fluid-loss control additive to the cement, which hopefullyreduces the ability of the liquid portion of the slurry from rapidlypenetrating a permeable zone at the formation face. This creates acritical dependence of the fluid control on the use of a fluid-losscontrol additive that functions at the temperature of the permeablezone. Also, the cement slurry must be designed to compliment therequirements of the fluid-loss additive for rheology of the fluidportion of the cement slurry. Most fluid-loss control additives thickenthe cement slurry they are mixed into. Also, they may retard thehardening of the cement when it reaches the destination. To deal withsuch properties it is common for service companies to have manydifferent fluid-loss control additives and to select the “best fit” forthe well conditions that are to be encountered.

What we have discovered and developed is a composition and method thatuses a two-stage process to allow the use of one “BorePrime” (such termis not meant as a limitation but as a short hand identification of theprocess) composition which can function as a pre-wash and “seeding” ofthe permeable zone of the formation face, and a second or follow-upcomposition which can be the actual cement slurry which contains thereactive “PrimeBloc” (such term is not meant as a limitation but as ashort hand identification of the process) composition. The “Prime”method is not as affected by temperature as most fluid-loss additivesand can function from near freezing 32° F. (0.0° C.) to above 400° F.(204.4° C.). Further enhancements of the base bore prime technology haveresulted in the discovery of mixtures, processes and compositionswhereby the fluid loss additive is capable of being added at about thesame time as the cement mixture.

“BorePrime” is to be used as a pre-wash or as a “spacer” additive ordrilling mud additive that is non-toxic and environmentally clean. As achemical wash the cost is very low compared to complex chemical washes.The “BorePrime” can be formulated as a non-thickened water base fluidthat will allow turbulent flow in the annulus at very low pump rates.The turbulent flow has been observed in laboratory simulations that showthe churning action that occurs at the front of the injected wash. Thedetergent action of the “BorePrime” together with the turbulent flowwill granulate the excess mud adhering to the pipe and the loose mud atthe formation face and carry the material out of the well. During thiscleaning action a “seeding” will take place at the formation face whichimpregnates the mud cake with “BorePrime” chemical. The concentrationwill vary depending on the permeability at the formation face; thehigher concentration typically going into the more permeable zones.

“BorePrime” can also be used in drilling mud or “spacers” to beavailable when later injection of “PrimeBloc” takes place. Thusfluid-loss control could be obtained without the necessity of the“BorePrime” wash, which in certain circumstances might not be desired.There is the possibility that a wash is not always an option if suchthings as disposal of fluids is an issue.

In various embodiments, “PrimeBloc” can be added to the cement mixtureas a dry or liquid fluid-loss control additive that requires a“BorePrime” wash to be used ahead or to be used when the drilling mud or“spacer” has previously carried the “BorePrime”. The “PrimeBloc” is alsovery low in cost compared to complex fluid-loss control additives andrequires an order of magnitude less material than conventionaladditives, in various embodiments because of the permeability blockoccurring at the formation-cement interface where the reaction of the“PrimeBloc” and “BorePrime” takes place. If the reaction had taken placein the cement slurry prior to reaching the permeable formation, theslurry would be much thicker and usually have to contain more water toreduce the viscosity of the reacted chemicals. Concentrating thereaction at the pressure-differential interface means the cement slurrydoesn't have to carry materials which can cause excessive viscosity orotherwise excessive amounts of fluid-loss control material. Likewisethis frees the slurry designer from the excess viscosity of mostfluid-loss control methods. Testing at the low temperatures has shownfluid-loss control with less than 0.1 percent fluid-loss controladditive in the “PrimeBloc” whereas a one stage fluid-loss test usingconventional methods and materials requires 1 percent or more.

In various embodiments, the discovery of a two-stage method and also thetype of chemicals in the method should be a significant improvement forfluid-loss prevention and permeable interface sealing. Such a techniquecould be utilized in any type of permeable situation to minimizeleak-off of fluid from a well-bore, pond, lake, or dam. In alternateembodiments, the use of an additive should result in significantimprovement for fluid loss prevention and permeable interface sealing.

Description of an Embodiment of Prime Technology

In various embodiments, this discovery has been proven in an embodimentusing a common crosslinker for polyvinyl alcohol (Borax) as the“BorePrime” active ingredient. The “PrimeBloc” active ingredient used inour laboratory work was PVA (polyvinyl alcohol). These materials havebeen used before as fluid-loss control agents but only as a combinedone-step package. When used as a pre-blended or combined fluid-losscontrol agent the reaction of cross-linking occurs in the cement slurryat the initial mixing time when water is added to the dry cementmaterials. As a result of this reaction in the early slurry life, thecross-linked reaction creates a fragile structure that is temperaturelimited to about 200° F. (93.3° C.) and requires a great excess offluid-loss material to control fluid loss. Also, the early reactioncreates viscosity increase and possible gellation of the slurry. Suchrheology problems increase the demands on pumping equipment and changesthe desired state of turbulent flow to plug flow or laminar flow.Turbulent flow is an accepted method to increase mud removal andsubsequent bond improvement.

Using borax as a pre-wash and primer for cross-linking a followingpolyvinyl alcohol has been documented in our laboratory testing underAmerican Petroleum Institute procedures as outlined in API RP 10publications. Variations from the strict test procedures were done inregard to simulation of a mud caked formation face as the permeableinterface for fluid-loss tests. The standard filter medium is 3.5 sq.in. in area. A 45 mm screen (No. 325) is supported by a 250 mm screen(No. 60). In order to simulate a mud covered formation face our testswere conducted by sandwiching a 1/16 smear of thick bentonite mudbetween Whatman No. 1 qualitative filter paper. The mud was soaked with2 ml of a solution containing 0.2 grams of borax. This “mud sandwich”was placed on the standard screen and fluid-loss tests were conducted asoutlined in API procedures. To verify the improved control of theinvention tests were run using the “mud sandwich” without borax andwithout the following polyvinyl alcohol.

Polyvinyl alcohol contents of less than 0.1 percent by weight of drycement used produced excellent fluid-loss control. The conventionalpre-crosslinked method uses as much as 10 times as much fluid-lossadditive. Temperature limits easily were above the 200° F. (93.3° C.)limit of conventional technique and were in fact found to extend to thebreak down temperature of the polyvinyl alcohol which is above 300° F.(148.9° C.) for the particular polyvinyl alcohol our testing wasutilizing. It is only logical that the temperature could exceed this fora material with higher temperature stability.

Mud Impregnated Screen

For testing, a modified filter has to retain Bore Prime chemical in sucha way as to simulate a cementing job that used the Bore Prime in apre-wash or spacer type application pumped ahead of a cement slurry.Simulating a permeable formation face that has a mud cake imbedded wasthe objective. To accomplish this a stainless screen without the 325mesh but with only the 60 mesh back-up was used as the base for thesimulation filter. Mud cake was a mixture of bentonite and water at apaste consistency that was layered across the back of the back-upscreen. A dose of approximately 1 ml of the Bore Prime wash was thenapplied to the mud face that was against the 60 mesh. Next, a Whatmanfilter (cat. # 1003-055) that had been pre-soaked and air dried was lainon the 60 mesh and wetted with 1 ml of the Bore Prime wash. The cap ofthe fluid-loss cell that the back-up screen attaches to was then pushedagainst the mud side of the back-up screen, allowing the mud to moveinto the 60 mesh screen and against the Whatman filter paper.

This prepared filter was then inserted in the fluid-loss cell and testedas required by API RP10b. If a test at moderate to high temperature wasto be run, then the prepared filter was held out of the fluid-loss celluntil the cell was ready to receive the cement slurry. This alternateprocedure is necessary to avoid dehydration of the mud cake on theprepared filter before testing.

Generally, any mock or simulated mud procedure can be used as long as acontrol is run.

Mud Sandwich

A “mud sandwich” filter can be used instead of the mud impregnatedscreen. To prepare this type filter use 60 mm diameter Whatman #3, whichcan be cut from (Whatman Cat No 1003 070) using a circle cutter such asAC-1 circle cutter from (www.buttonsonline.com). Use two papers with alayer of mud paste (100 g bentonite in 500 ml water) between themapproximately 2 mm thick. The mud and papers should be dosed with BorePrime wash made from 1 gram of Bore Prime in 100 ml of fresh water. This“mud sandwich” should be attached to the stainless screen using mud asan adhesive to hold the sandwich during assembly of the fluid-loss cellprior to running the fluid-loss test. As before mentioned, do notpreheat this sandwich since it will dehydrate. Add it to the cell justbefore adding the cement slurry.

Results

Slurry and mud compositions:

Prime Bloc: Lehigh class H cement Retarders HR-5, HR-12, SCR-100, PrimeBloc 1 PVA (polyvinyl alcohol) about 55%-about 65% Albaglos PCC about35%-about 45% A precipitated calcium carbonates (PCCs) designed forcoated paper and paperboard applications. Defoamer about 1% 40208pva (3parts Elvanol 71-31 pva, 3 parts Elvanol 50-42s8pva, 4 partsprecipitated CaCO₃) Filters: 32008a(Whatman qualitative #3), EX-1(0.4parts borax, 100 parts water), 40408a (12 parts boric acid, 300 partswater), 40408c (16 parts borax, 4 parts dish detergent WalMart GV), mudwas made from bentonite/water paste, salty mud had 40 parts bentonitepaste + 10 parts NaCl) Filters were permeable paper or mud smears thathad Bore Prime chemical. PVA: Dupont Elvanol 50-42S8 Wilmington, DE.302-478-5491 Eliot Echt (1-302-478-5491) Albaglos PCC: SpecialtyMinerals Inc.Adams, MA. 413-743-0591 Mark Spurlock (1-281-658- 6954)Defoamer DF: BASF Global Oilfield Solutions, Houston, Tx. 281; 820-0955Bore Prime: Borax Decahydrate Granular about 65%-about 85% Auto DishDetergent about 15%-about 35% Borax: U.S. Borax Inc., 26877 TourneyRoad, Valencia, CA 91355-1847, Larry Jayroe, Rio Tinto Minerals, U.S.Borax, Inc./Luzenac P.O. Box 1093, Forrest City, AR 723336, Phone870.630.0895, Auto Dish Detergent: Wal-Mart Great Value AutomaticDishwashing Detergent Huish Detergents, Inc. 3540 W/ 1987 S.. Salt LakeCity, UT 84104

Experiment 1

Fluid Loss Viscosity Sample Slurry Composition Temp ° F. (ml/time)(Bearden units) LW540-3 Lehigh + 0.5% (Primebloc 1) + 150  47/103 sec. 6(initial) 17 (final) 0.2% HR-5 + 44% water (32008a filter used) LW540-4Lehigh + 0.75% (Primebloc 1) + 150  34/30 min.  6 15 0.2% HR-5 + 44%water (32008a filter used) LW540-6 Lehigh + 0.75% (Primebloc 1) + 190 41/18 sec. 12 34 0.08% HR-12 + 54% water (32008a filter used) LW540-7Lehigh + 1% (Primebloc 1) + 190  39/45 sec. 12 36 0.08% HR-12 + 54%water (32008a filter used) LW540-8 Lehigh + 1.25% (Primebloc 1) + 190 41/43 sec. 12 35 0.08% HR-12 + 54% water (32008a filter used) LW540-9Lehigh + 1.25% (Primebloc 1) + 190  32/165 sec. 13 23 0.08% SCR-100 +54% water (32008a filter used) LW541 Lehigh + 1% (40208pva) + 0.08% 190 44/25 sec. 12 35 HR-12 + 35% silica flour + 54% water (using 32008afilter) LW542 Lehigh + 1.25% (Primebloc 1) + 190  42/43 sec. 11 22 0.08%SCR-100 + 35% silica flour + 54% water (using 32008a filter) LW540bLehigh + 1.5% (Primebloc 1) + 190 26/1126 sec. 12 20 0.08% SCR-100 + 35%silica flour + 54% water (using 32008a filter) LW540b-2 Lehigh + 1.25%(Primebloc 1) + 190  37/81 sec. 12 20 0.08% SCR-100 + 35% silica flour +54% water (using 32008a filter) LW540b-3 Lehigh + 1.75% (Primebloc 1) +190  47/30 min. 12 20 0.08% SCR-100 + 35% silica flour + 54% water(using 32008a filter) Lehigh + 1.67% (Primebloc 1) + 190  33/307 sec. —— 0.08% SCR-100 + 35% silica flour + 54% water (using 32008a filter)LW543 Lehigh + 1.58% (Primebloc 1) + 190  30/865 sec. 21 30 0.08%HR-12 + 35% silica flour + 54% water (using EX-1 filter) LW540b-5Lehigh + 2.25% (Primebloc 1) + 230  76/32 sec. — — 0.5% HR-12 + 35%silica flour + 54% water (using 3200a filter) Lehigh + 2.25%(Primebloc 1) + 230  33/30 min. — — 0.5% HR-12 + 35% silica flour + 54%water (using 40408a filter 1) LW540c Lehigh + 2.5% (Primebloc 1) + 270 12/30 min. 15 10 0.67% HR-12 + 35% silica flour + 54% water (using40408c filter) LW540c-2 Lehigh + 2.5% (Primebloc 1) + 300 115/552 sec.15 10 0.83% HR-12 + 35% silica flour + 54% water (using 40408c filter)LW540c-4 Lehigh + 2.75% (Primebloc 1) + 325   1.7/30 min. — — 0.83%HR-12 + 35% silica flour + 54% water (using 40408c filter against mudsmear on 60 mesh wire screen without 325 wire screen) LW540c-5 Lehigh +2.75% (Primebloc 1) + 350  70/66 sec. — — 0.83% HR-12 + 35% silicaflour + 54% water (using 40408c filter against mud smear on 60 mesh wirescreen without 325 wire screen) LW540c-6 Lehigh + 3.25% (Primebloc 1) +350  94/171 sec. — — 0.83% HR-12 + 35% silica flour + 54% water (using40408c filter against mud smear on 60 mesh wire screen without 325 wirescreen) LW540 Incor HE + 0.25% (Primebloc 1) + 80  47/30 min. 20 40 48%water (using 32008a filter) LW540-2 Incor HE + 0.25% (Primebloc 1) + 100 24/30 min. 15 40 50% water (using 32008a filter) LW540-5 Incor HE +0.16% (Primebloc 1) + 80  55/30 min. 12 30 50% water (using 32008afilter) LW540d Lehigh + 2.5% (Primebloc 1) + 310  55/30 min. — — 0.83%HR-12 + 35% silica flour + 54% water (using 40408c filter sandwiched onmud smear) LW540b-6 Lehigh + 2% (Primebloc 1) + 0.5% 250  16/30 min. — —HR-12 + 35% silica flour + 54% water (using 40408c filter sandwiched onmud smear) LW540b-7 Lehigh + 0% (Primebloc 1) + 0.5% 250  148/65 sec. —— HR-12 + 35% silica flour + 54% water CONTROL TEST (using 40408c filtersandwiched on mud smear) LW540b-8 Lehigh + 2% (Primebloc 1) + 0.5% 230  4/30 min. — — HR-12 + 35% silica flour + 54% water (using 40408cfilter sandwiched on mud smear using 60 mesh wire, no 325 mesh) LW540b-9Lehigh + 1.5% (Primebloc 1) + 230  55/30 min. — — 0.5% HR-12 + 35%silica flour + 54% water (using 40408c filter sandwiched on mud smear)LW540c-7 Incor HE + 0.125% (Primebloc 1) + 80 blew out too rapidly — —48% water to measure (using 40408c filter with mud smear against 60 meshback-up screen) 2^(nd) test (using 40408c filter with 80  70/30 min. — —mud smear against standard back- up screen, 60 mesh on 325 mesh)LW540c-8 Incor HE + 0.167% (Primebloc 1) + 80 43/1123 sec. — — 50% water(using two 40408c filters against standard back-up screen, 60 mesh on325 mesh) 2^(nd) test (using two 40408c filters 80  45/85 sec. — —against standard back-up screen, 60 mesh on 325 mesh)- LW540c-9 IncorHE + 0.125% (Primebloc 1) + 80  38/303 sec. — — 50% water (using two40408c filters against 60 mesh back-up screen) LW540c- Incor HE + 0.25%(Primebloc 1) + 80  47/121 sec. — — 10 50% water (using two 40408cfilters against 60 mesh back-up screen) 2^(nd) test (using two 40408cfilters 80  52/30 min. — — against standard 60 mesh on 325 mesh)-LW540c- Incor HE + 0.25% (Primebloc 1) + 80  44/30 min. — — 11 50% water(using two 40408c filters as a sandwich on mud smear against 60 meshwithout 325 mesh) 2^(nd) test (using two 40408c filters 100  45/30 min.— — as a sandwich on mud smear against 60 mesh without 325 mesh)-LW540c- Lehigh + 3.25% (Primebloc 1) + 350 blew out gummy liquid in 69sec, used 12 0.83% HR-12 + 35% silica flour + 500 psi test pressure 54%water (using two 40408c filters as a sandwich on mud smear against 60mesh without 325 mesh) LW540c- Lehigh + 3.25% (Primebloc 1) + 350 blewout gummy liquid in 79 sec., used 12 0.83% HR-12 + 35% silica flour +500 psi test pressure 54% water (using two 40408c filters as a sandwichon salty mud smear against 60 mesh without 325 mesh)

Experiment 2

tests at Lab 1000 psi Viscosity Work Fluid Loss (Bearden ID Composition(ml/time)* units)** LW511 Prime Bloc 2 (21% PVA, 78% CaCO₃, 1% defoamer)NA NA LW512 Lafarge + 0.7% (Primebloc 2) + 46% water (using Bore Prime1^(st) 58/ 12 20 filter EX1) test 30 min (initial) (final) 2^(nd) 38/ —— test 30 min LW513 Lafarge + 0.7% (Primebloc 2) + 46% water (using BorePrime 1^(st) 37/ 11 17 filter EX2) test 30 min 2^(nd) 41/30 min — — testLW521 Lafarge + 0.7% (Primebloc 2) + 46% water (using Bore Prime filter1^(st) 34/ 10 18 31208) test 30 min (tested at 2^(nd) 49/ — — 110° F.)test 30 min LW531 Lafarge + 0.7% (Primebloc 2) + 46% water (using BorePrime filter 1^(st) 50/ 12 18 32008b) test 30 min (tested at 2^(nd) 36ml/ — — 125° F.) test 337 sec. LW533 Lafarge + 0.7% (Primebloc 2) +0.067% HR-4 + 46% water (tested 39 ml/ 10 31 at 125° F., using 32008afilter) 1345 sec. Lafarge + 0.7% (Primebloc 1) + 0.067% HR-4 + 46% water(tested 29/30 min 10 25 at 125° F., using 32008a filter) LW534 Lafarge +0.7% (Primebloc 2) + 0.067% HR-4 + 48% water (tested 63/30 min  9 21 at125° F., using 32008a filter) Lafarge + 1% (Primebloc 2) + 0.067% HR-4 +48% water (tested at 55/30 min 10 21 125° F., using 32008a filter) LW535Lafarge + 0.7% (Primebloc 2) + 0.1% HR-4 + 48% water (tested at 46 ml/15sec.  5 20 175° F., using 32008a filter) Lafarge + 1% (Primebloc 2) +0.1% HR-4 + 48% water (tested at 57 ml/18 sec.  5 18 175° F., using32008a filter) Note: Test temperature was 80° F. unless otherwise noted.Primebloc 2; 0.7% Prime Bloc 2 is about the equivalent of 0.147% PVA.Prime Bloc 1 is a higher PVA composition (sample 389, 59% PVA, 40%precipitated CaCO3, 1% defoamer) Lafarge type I cement was used in thetests. Test LW527 was held at 1000 psi for 15 min before opening valvestem very slightly attempting to study effect on fluid loss rate.IRF-105 is a Tucker Energy Services fluid loss additive seen as acompetitive product. HR-4 is a retarder, as might be available fromHalliburton. Defoamer was commercial powder grade. *Fluid loss wasconducted according to API RP 10 with the exception of when “Prime”filters were used to apply reactive chemical to the fluid as it enteredthe permeable membrane (filter screen). Control tests have shown the“Prime” filter offers no blockage to fluid without the PVA containingsecondary reaction product entering the screen. **Viscosity was takenfrom the atmospheric consistometer that was used to stir the cementslurry before testing in the high pressure fluid loss cell.

1.-14. (canceled)
 15. A method for inhibiting fluid loss from an oil andgas well, said method comprising the steps of, separately: washing awell borehole with a wash composition, said wash composition comprisinga cross linking agent, wherein said cross linking agent at leastpartially impregnates a formation's face and pumping a cement mixtureinto said well's borehole to cement at least a portion of a formationface, said cement mixture comprising a polymer composition, wherein saidpolymer polymerizes in, on, or about said formation's face upon exposureto said cross linking agent, thereby inhibiting fluid loss from saidwell's borehole to said formation.
 16. The method of claim 15, whereinthe step of washing at least partially cleans the well of excess mud.17. The method claim 15, wherein the step of washing at least partiallyimpregnates at least one of said borehole's tubing and said borehole'sformation face with said cross linking agent.
 18. The method of claim15, wherein said cross linking agent is added to said well boreholealong with an oil-based drilling mud or “spacer”.
 19. The method ofclaim 15, wherein said cross linking agent is at least one of borax,boric acid, water soluble borates, sodium borates, calcium borates,potassium borates, titanates, zirconates, and mixtures thereof.
 20. Themethod of claim 15, further comprising the step of: adding fineparticulate material to the polymer composition prior to mixing it withthe cement mixture.
 21. The method of claim 20, wherein the fineparticulate material is calcium carbonate.
 22. The method of claim 15,wherein the polymer is at least one of polyvinyl alcohol or a lowviscosity partially hydrolyzed polyvinyl alcohol such as DuPontElvanol(R) 51-05S8.
 23. A method for inhibiting fluid loss from an oilor gas well, said method comprising the steps of, separately: washing awell with a reactant agent that creates a thickened reaction productwhen a secondary mixture is encountered, and adding secondary mixture tothe well's borehole which forms a thickened reaction product uponexposure to said reactant, thereby inhibiting fluid loss from saidwell's borehole to a formation adjacent to said well borehole.
 24. Themethod of claim 15, wherein the step of washing is removed and saidcross linking agent is included with a drilling fluid circulated in saidwell's borehole prior to adding said cement mixture.
 25. A kit forinhibiting fluid loss from an oil and gas well comprising: a washcomposition, said wash composition comprising a cross linking agent anda polymer composition, wherein said polymer polymerizes in, on, or abouta formation's face upon exposure to said cross linking agent, therebyinhibiting fluid loss from said well's borehole to said formationthrough said formation's face.
 26. A polymerized well borehole, saidpolymerized well borehole formed by a method of claim
 15. 27. A methodfor reducing an amount of fluid loss additive necessary to inhibit fluidloss from an oil and gas well, said method comprising the steps of,separately: washing a well borehole with a wash composition, said washcomposition comprising a cross linking agent, wherein said cross linkingagent at least partially impregnates a formation's face and pumping acement mixture into said well's borehole to cement at least a portion ofa formation face, said cement mixture comprising a polymer composition,wherein said polymer polymerizes in, on, or about said formation's faceupon exposure to said cross linking agent, thereby inhibiting fluid lossfrom said well's borehole to said formation through said formation'sface, wherein between about 0.1% and about 90% by volume of acontemporary fluid loss additive is used to inhibit fluid loss.
 28. Themethod of claim 27, wherein said fluid loss additive's components arethe same as the components of the contemporary fluid loss additive. 29.The method of claim 27, wherein the step of washing is removed and saidcross linking agent is included with a drilling fluid circulated in saidwell's borehole prior to adding said cement mixture.
 30. The method ofclaim 15, wherein said cement mixture comprises a permeable,micro-cluster silica material present in an amount from about 10 percentto about 30 percent by weight of the cement mixture, wherein saidpermeable, micro-cluster silica material has an average particle sizeranging from about 30 to about 80 microns and a range of distributionfrom about 1 micron to about 200 microns.
 31. The kit of claim 25,further comprising: a permeable, micro-cluster silica material, whereinsaid permeable, micro-cluster silica material has an average particlesize ranging from about 30 to about 80 microns and a range ofdistribution from about 1 micron to about 200 microns.
 32. The method ofclaim 23, wherein the step of washing is removed and said cross linkingagent is included with a drilling fluid circulated in said well'sborehole prior to adding said cement mixture.
 33. A polymerized wellborehole, said polymerized well borehole formed by a method of claim 23.34. The method of claim 23, wherein said cement mixture comprises apermeable, micro-cluster silica material present in an amount from about10 percent to about 30 percent by weight of the cement mixture, whereinsaid permeable, micro-cluster silica material has an average particlesize ranging from about 30 to about 80 microns and a range ofdistribution from about 1 micron to about 200 microns.
 35. The method ofclaim 27, wherein said cement mixture comprises a permeable,micro-cluster silica material present in an amount from about 10 percentto about 30 percent by weight of the cement mixture, wherein saidpermeable, micro-cluster silica material has an average particle sizeranging from about 30 to about 80 microns and a range of distributionfrom about 1 micron to about 200 microns.